Externally supported lye tank

ABSTRACT

An article of manufacture that includes a lye tank and an external support structure attached thereto is described. The lye tank has a base having an aperture and sidewalls extending upwardly there from, and an open end. The lye tank may be fabricated from metal and/or plastic. The external support structure includes: (i) at least one bowl-shaped profile member having a base and sidewalls and an interior space; (ii) a plurality of plastic reinforcing ribs located fixedly within the interior space of the bowl-shaped member; and (iii) a connecting member, having an opening, which is connected to the first end of the bowl-shaped member by means of positive and/or material connections. The lye tank and the external support structure are connected together such that aperture of base of tank is aligned with opening of connecting member. External surfaces of base of bowl-shaped member face and extend along (and optionally abut) the external surfaces of base and sidewalls of lye tank.

CROSS REFERENCE TO RELATED PATENT APPLICATION

The present patent application claims the right of priority under 35 U.S.C. §119 (a)-(d) of German Patent Application No. 103 35 972.9, filed Aug. 6, 2003.

FIELD OF THE INVENTION

The invention relates to a lye tank with supporting structure for washing machines.

BACKGROUND OF THE INVENTION

The construction of a front-loading drum-type washing machine with a lye tank has been known for a long time and is described for example in DE 197 52 296 A1. In drum-type washing machines a perforated washing drum is mounted rotatably at one side in a lye tank. The tank is in turn mounted resiliently in a casing. The casing has an operating switch cover and a loading aperture at the front. The circular loading aperture for the washing drum is surrounded by a tube-like concertina seal which is attached firstly to the lye tank and secondly to the edge of the loading aperture. The loading aperture can be closed tightly by a porthole which is mounted for pivoting motion. The tank is connected to a detergent washing-in chamber. A lye outlet is fitted in the region of the base of the tank and leads to an emptying pump. A motor is provided to drive the washing drum mounted horizontally in the tank.

Rotatable drums mounted at one side and surrounded by a cylindrical tank are also used for example in laundry dryers or centrifuges. One of the functions of the cylindrical lye tank is to absorb the centrifugal and axial forces occurring during rotation of the drum and transmit them for example to the casing of the washing machine. For this purpose the tank is held resiliently in the casing of the washing machine by suspension or attachment points.

Lye tanks known from the state of the art are made of one material, either plastics material or sheet steel, and produced for example by an injection moulding or welding process.

Development of washing machines has more recently lead to ever higher washing drum speeds and ever higher drying temperatures together with the quietest possible operation, and in addition production costs for washing machine components have to be reduced.

SUMMARY OF THE INVENTION

The object of the present invention is therefore to provide a lye tank which can be exposed to stronger forces during operation of the washing machine and which can be produced simply and cost-effectively.

According to the invention, the object is achieved in that the lye tank is constructed in two parts, i.e., made up of the lye tank itself and an external supporting structure which receives the lye tank.

In accordance with the present invention, there is provided an externally supported lye tank comprising:

-   -   (a) a lye tank (10) having a base (12) and sidewalls (14)         extending away from said base (12), and having an open end (50),         the base (12) of said lye tank (10) having an aperture (11)         therein, said lye tank being fabricated from a material selected         from the group consisting of metal, plastic-and combinations         thereof, the base (12) and sidewalls (14) of said lye tank (10)         each having external surfaces (53 and 56 respectively); and     -   (b) an external support structure (20) comprising,         -   (i) at least one bowl-shaped profile member (21) having a             base (59) and sidewalls (62) extending away from said base             (59), said bowl-shaped profile member (21) having an open             end (65), the sidewalls (62) and base (59) of said             bowl-shaped profile (21) having internal surfaces (68 and 71             respectively) which together define an interior space (74)             of said bowl-shaped profile (21), said base (59) of said             bowl-shaped profile member having an external surface (77),             said bowl-shaped profile being-fabricated from a material             selected from the group consisting of metal, plastic and             combinations thereof, and said bowl-shaped profile member             having a first end (22) and a second end (23),         -   (ii) a plurality of plastic reinforcing ribs (42) located             within said interior space (74) of said bowl-shaped profile             (21), said plastic reinforcing ribs (42) being fixedly             attached to said bowl-shaped profile member (21) by means             selected from the group consisting of positive connections,             material connections and combinations thereof; and         -   (iii) a connecting member (30) having an opening (33), said             connecting member (30) being connected to the first end (22)             of said bowl-shaped profile member (21) by means selected             from the group consisting of positive connections, material             connections and combinations thereof,             wherein said lye tank (10) and said external support             structure (20) are joined together such that the aperture             (11) in the base (12) of said lye tank (10) is aligned with             the opening (33) of said connecting member (30), the             external surfaces (77) of the base (59) of bowl-shaped said             profile member (21) facing and being arranged along (and             optionally abutting) the external surfaces (53 and 56) of             said base (12) and said sidewalls (14) of said lye tank             (10).

The features that characterize the present invention are pointed out with particularity in the claims, which are annexed to and form a part of this disclosure. These and other features of the invention, its operating advantages and the specific objects obtained by its use will be more fully understood from the following detailed description and accompanying drawings in which preferred embodiments of the invention are illustrated and described.

Unless otherwise indicated, all numbers or expressions used in the specification and claims are understood as modified in all instances by the term “about.”

As used herein and in the claims, the term “positive connection” and similar terms refers to the fixed joining of two or more members (elements) together by means of molded-on plastic material passing: (i) through perforations in at least one of the members; (ii) around the edges (terminal edges) of at least one of the members; and/or (iii) over bumps (e.g., beads or ribs) in/on at least one of the members. The molded-on plastic material embeds the edges of the perforations and/or the edges and/or the bumps of the members therein.

As used herein and in the claims, the term “material connection” and similar terms refers to the fixed joining of two or more members (elements) together by means selected from fasteners, snap fittings, clip-on fittings, adhesives and/or thermoplastic welds.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a representative perspective view of an embodiment of the external supporting structure according to the invention with three bowl-shaped profile members (21) and a connecting member (30), before the plastic reinforcing ribs (42) are injected thereon;

FIG. 2 is a representative perspective view of the external support structure of FIG. 1 with reinforcing ribs (42) and ring (40);

FIG. 3 is a representative perspective view of the external support structure (20) of FIG. 2 and a lye tank (10), before the two components are joined together; and

FIG. 4 is a representative perspective view of the external support structure (20) and lye tank (10) of FIG. 3 after they have been joined together.

In FIGS. 1 through 4, like reference numerals designate the same components and structural features.

DETAILED DESCRIPTION OF THE INVENTION

The subject of the invention is a lye tank with a supporting structure (i.e., an external support structure), wherein the lye tank, made of metal or plastics material with an external wall, has an aperture in the base, the supporting structure at least comprises a bowl-shaped, substantially right-angled profile made of metal or plastics material with plastic reinforcing ribs and a connecting member with an opening, the profile being joined at one end to the connecting member with a positive and/or material connection, and the supporting structure and lye tank are joined together in such a way that the aperture and the opening are in register and the profile is arranged along the external wall of the lye tank.

The lye tank to receive the washing drum is substantially cylindrical. It is open at one side and has an aperture on the opposite side in the base of the tank, preferably in the centre of the base, to receive the drive bearing for the washing drum. The aperture is preferably substantially round although it may be of any other shape. When fitted in a washing machine the lye tank has to be sealed off from the environment. It accommodates a concertina seal at its open side. The aperture in the base of the tank is similarly provided with a seal in the installed condition.

The lye tank is made of a material resistant to chemicals and heat, particularly metal or plastics material. The plastics materials used may be non-reinforced, reinforced and/or filled thermoplastic polymers, preferably polycarbonate (PC), thermoplastic polyurethane (PU), polyester, particularly polyethylene terephthalate (PET), polystyrene (PS), syndiotactic polystyrene, acrylonitrile butadiene styrene (ABS), polypropylene oxide (PPO), polysulphone (PSO), polyphenylene sulphide (PPS), polyimide (PI), polyketone (PEEK), polyamide (PA), polybutylene terephthalate (PBT), polypropylene (PP), polyethylene (PE) or a mixture of these plastics materials.

The metals used may be steel, nickel, chromium, iron, copper, zinc, titanium, aluminium or magnesium, and alloys of those metals.

The lye tank is preferably produced from polypropylene or polyethylene.

The lye tank may be produced by known methods. In the case of a plastics tank it may be made for example by blow moulding, vacuum forming, rotational moulding or injection moulding processes such as thin-wall injection moulding. A metal lye tank may be produced for example by deep drawing or welding.

The supporting structure to receive the lye tank at least comprises a bowl-shaped profile made of metal or plastics material with plastic reinforcing ribs and a connecting member. The supporting structure is preferably made up of three profiles, which have substantially right-angled sidewalls relate to the base of the profile. One end (e.g., the first end) of the profile is joined to the connecting member, which has an opening to receive the drive bearing for the washing drum. If a plurality of profiles are provided, one end of each is joined to the connecting member. The profiles are preferably arranged at equal intervals (e.g.; circumferentially) along (or around) the periphery of the connecting member. If two profiles are provided they are accordingly arranged preferably diametrically.

The connecting member may have any geometry. It may for example be round, rectangular or triangular. The opening to receive the bearing for the washing drum is preferably cylindrical.

When the lye tank is being joined to the supporting structure the two parts are arranged so that the opening in the connecting member and the aperture in the base of the tank are brought into register (i.e., they are aligned one with the other). The profile of the supporting structure simultaneously leads along the external wall of the lye tank. The substantially right-angled profile engages round the lye tank and hence—in cases where the aperture is in the centre of the base of the tank—the length of the base portion of the profile arms (83), i.e., that portion of each bowl-shaped profile member (21) that extends along the external surface (53) of base (12) of lye tank (10), joined to the connecting member is substantially equal to the external radius of the cylindrical lye tank. The length of the sidewall portion of the profile arms (86), i.e., that portion of each bowl-shaped profile member (21) that extends along the external surface (56) of sidewalls (14) of lye tank (10), with the free end (e.g., the second end) of the profile is substantially equal to the height of the lye tank.

A plastic ring may be arranged at the second, free end of the profile, i.e. the end not joined to the connecting member. If the lye tank and supporting structure are joined together the plastic ring locks with the edge of the lye tank at its open side, and forms the seat for the concertina seal together with the tank. If a plurality of profiles are provided they are interconnected by the ring at their free ends, thereby increasing stability.

The function of the supporting structure is to transmit centrifugal and axial forces from the rotating drum to the casing of the washing machine. For this purpose the supporting structure has attachment or suspension points at which it is joined resiliently to the casing. These points act as load lead-out locations.

The connecting member which receives the drive bearing, for example the sliding or ball bearing for the washing drum is preferably made of metal, particularly steel, nickel, chromium, iron, copper, zinc, titanium, scandium, aluminium or magnesium, or alloys of these metals. It may equally be made of a reinforced and/or filled thermoplastic polymer, particularly polycarbonate (PC), thermoplastic polyurethane (PU), polyester, particularly polyethylene terephthalate (PET), polystyrene (PS), syndiotactic polystyrene, acrylonitrile butadiene styrene (ABS), polypropylene oxide (PPO), polysulphone (PSO), polyphenylene sulphide (PPS), polyimide (PI), polyketone (PEEK), polyamide (PA), polybutylene terephthalate (PBT), polypropylene (PP), polyethylene (PE) or a mixture of these plastics materials. Carbon fibres and glass fibres may for example be used as reinforcing materials.

The bowl-shaped profile may for example be I, U, L, T or double T-shaped. It is produced from metal, particularly steel, nickel, chromium, iron, copper, zinc, titanium, scandium, aluminium or magnesium or alloys of these metals, or from a reinforced and/or filled thermoplastic polymer, particularly polycarbonate (PC), thermoplastic polyurethane (PU), polyester, particularly polyethylene terephthalate (PET), polystyrene (PS), syndiotactic polystyrene, acrylonitrile butadiene styrene (ABS), polypropylene oxide (PPO), polysulphone (PSO), polyphenylene sulphide (PPS), polyimide (PI), polyketone (PEEK), polyamide (PA), polybutylene terephthalate (PBT), polypropylene (PP), polyethylene (PE) or a mixture of these plastics materials. Carbon fibres and glass fibres may for example be used as reinforcing materials.

The profile is produced for example by punching, deep drawing, bevelling, casting or injection moulding processes.

Internally the bowl-shaped profile has reinforcing ribs of thermoplastic, particularly non-reinforced, reinforced and/or filled plastics material based on polyamide (PA), polyester, particularly polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), syndiotactic polystyrene, acrylonitrile butadiene styrene (ABS), polybutylene terephthalate (PBT), thermoplastic polyurethane (PU), polyolefin, particularly polypropylene (PP), polyethylene (PE), polycarbonate (PC), polypropylene oxide (PPO), polysulphone (PSO), polyphenylene sulphide (PPS), polyimide (PI), polyether etherketone (PEEK) or a mixture of these plastics materials.

The reinforcing ribs are preferably joined to the profile with a positive connection, particularly by means of injected thermoplastic. Ribs of this type are known from DE 38 39 855. The reinforcing-ribs are joined to the profiles for example by means of plastic riveted joints, the profiles being provided with openings (perforations having edges) and/or beads into which the ribs are injected

In a further embodiment the reinforcing ribs are joined to the profiles with a material connection, particularly by adhesion or welding. The ribs may also be joined non-positively to the profiles, in particular by means of a plug-in or clip-on connection.

The profile is joined to the connecting member with a positive and/or material connection.

The profile may be joined to the connecting member for example through the connecting member having an edge region along the outer periphery, standing substantially perpendicularly on the tubular wall. The edge region may both extend along the whole periphery of the connecting member and also be divided into partial regions positioned according to the arrangement of the profile or profiles. The edge region of the connecting member is provided with openings. The profile may for example likewise have an edge region with openings at the end joined to the connecting member. The openings in the edge region of the profile and those in the edge region of the connecting member are superimposed for joining. Cup impressions are formed in the region of the openings in the profile. The cup impressions allow a positive connection without any play between the connecting member and the profile. Alternatively or in addition to the openings with or without impressions in the edge region of the connecting member and the edge region of the profile, beads may also be provided, similarly allowing the profiles to be positively connected to the connecting member.

Additionally or alternatively an adhesion or welded joint may for example provide a material connection between the connecting member and the profile.

In addition to the positive and, if appropriate, material connection between the connecting member and the profile, thermoplastic may be injected through and around the openings to achieve the desired tenacity. The same plastics material may be used for the injection of thermoplastic as for the reinforcing ribs.

The ring joined to the free end of the profiles is preferably made of the same plastics material as the reinforcing ribs. It may however, independently of the ring (sic), be made of a non-reinforced, reinforced and/or filled thermoplastic, particularly based on polyamide (PA), polyester, particularly polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), syndiotactic polystyrene, acrylonitrile butadiene styrene (ABS), polybutylene terephthalate (PBT), thermoplastic polyurethane (PU), polyolefin, particularly polypropylene (PP), polyethylene (PE), polycarbonate (PC), polypropylene oxide (PPO), polysulphone (PSO), polyphenylene sulphide (PPS), polyimide (PI), polyether etherketone (PEEK) or a mixture of these plastics materials.

Adjacent the annular edge at the free ends of the profiles further frame elements may be joined to the profiles, for example in the angled region, in order to increase stability. The annular edge and optionally further plastic frame elements are preferably joined to the profiles with a positive connection and/or a material connection by means of adhesive, by injecting around and through them.

The lye tank is permanently or detachably joined to the supporting structure. It is preferably joined detachably to the structure by plugging in, screwing, clipping on, riveting or with a bayonet connection. This enables the lye tank to be installed in and removed from the casing of the washing machine, for example for cleaning or repair purposes, independently of the supporting structure.

The supporting structure is produced by inserting the profiles and connecting member into the injection mould. The injection of the reinforcing ribs onto the profiles, the injection through and around the openings to join the connecting member to the profiles, and the injection of the ring and optionally further frame elements or the like take place in one operation without any post-treatment.

An advantage of the lye tank with a supporting structure according to the invention is that, owing to the two-part construction made up of the lye tank and supporting structure, each of the two parts can be produced from the most suitable material, with the most cost-effective technology and by the most cost-effective method. The composite plastic-metal structure also allows simpler modification. The lye tank itself may be removed from the casing of the washing machine for repair or cleaning purposes independently of the supporting structure. In addition the lye tank of composite plastic-metal structure has greater structural rigidity, a higher load-carrying capacity and higher component precision than a lye tank made purely of plastics material. Sound insulation is greater and the number of components lower compared to a lye tank made of sheet steel. There is thus a clear reduction in production times and production costs.

The invention will now be illustrated in greater detail with reference to the accompanying drawings in which like components carry like references.

Three bowl-shaped, substantially right-angled profiles 21 and a cylindrical connecting member 30 with an opening 33 are illustrated in FIG. 1. The function of the cylindrical opening 33 in the connecting member 30 is to receive the drive bearing for the washing drum (not shown). The bowl-shaped profiles 21 are each arranged on the connecting member 30 at one end 22 at equal distances along the periphery. The free ends 23 of the profiles 21 point in the same direction to receive the cylindrical lye tank. The connecting member 30 has edge regions 31 with openings 32 and edge regions 35 with openings 34, at which the profiles 21 are joined to the connecting member 30. For this purpose the profiles 21 have an edge region 24 with openings 25 which register with the openings 32 in the connecting member 30, and an edge region 28 with openings 27 which register with the openings 34. A positive connection with shear strength is obtained between the profiles 21 and the connecting member 30 by stamping.

With further reference to FIG. 1, bowl-shaped profile members (21) each have sidewalls 62 that extend away from base 59 at substantially right angles. Sidewalls 62 may extend away from base 59 at angles (relative to base 59) of greater than 0° and less than 180°, e.g., from 45° to 135°, typically from 60° to 110°.

FIG. 2 shows the supporting structure 20 made up of the connecting member 30 and the profiles 21 positively connected thereto according to FIG. 1, after the injection of thermoplastic. In the edge regions 31, 35 of the connecting member 30 and the edge regions 24, 28 of the profiles 21 (FIG. 1) plastics material is injected through and around 43 the openings 32, 25 and 32 and 34, 27. The reinforcing ribs 42 are further injected into the profiles 21. A plastic ring 40 is also injected in the region of the free ends 23 of the profiles 21 to interconnect them. In this special embodiment a further annular plastic frame element 41 is injected in the angled region 26 of the profiles 21 and similarly interconnects the three profiles 21.

FIG. 3 reproduces the supporting structure 20 shown in FIG. 2, comprising three profiles 21 with reinforcing ribs 42, the connecting member 30 with the opening 33, the edge 40 and the annular frame element 41. The cylindrical lye tank 10 is also shown, before it is joined to the supporting structure 20. The tank 10 with an external wall 14 has a round aperture 11 in the base 12 of the tank. When the tank 10 is joined to the supporting structure 20 the round aperture 11 is brought into register with the opening 33 in the connecting member 30. The tank 10 has an outwardly-directed peripheral edge (annular flange) 13 at its open side (i.e., at the upper terminal portions of sidewalls 14).

FIG. 4 shows the lye tank 10 and supporting structure 20 according to FIG. 3 after they have been joined. The annular edge region 40 of the structure 20 locks with the edge 13 of the lye tank 10, with the edge 13 lying on the ring 40. The edge 13 has a seat for the concertina seal (not shown) which is supported by the edge region 40. The profiles 21 engage around the lye tank 10 and lead along its external wall 14.

In an embodiment of the present invention, and with further reference to FIGS. 1-4, sidewalls (62) and base (59) of bowl-shaped profile member (21) have a plurality of perforations (not shown) having edges. The plastic reinforcing ribs (42) are formed by injection molding thermoplastic material onto the internal surfaces (68 and 71 respectively) of sidewalls (62) and base (59) of bowl-shaped profile member (21). During the injection molding procedure, a portion of the injected-on thermoplastic material extends through the perforations (not shown) in the base (59) and sidewalls (62) of bowl-shaped profile member (21). The edges of the perforations (not shown) become embedded in the thermoplastic material extending there through, thereby fixedly attaching the reinforcing ribs (42) to bowl-shaped profile member (21) (by means of one form of positive connections).

In a particularly preferred embodiment of the present invention, and with further reference to FIG. 4, the bowl-shaped profile member (21) has a base arm portion (83) that is adjacent to and extends along base (12) of lye tank (10), and a sidewall arm portion (86) that is adjacent to and extends along sidewall (14) of lye tank (10). The base arm portion (83) and the sidewall arm portion (86) of bowl-shaped profile member (21) are continuous with each other, and form an angle relative to each other, e.g., at elbow portion (89), of greater than 0° and less than 180°, e.g., from 45° to 135°. In an embodiment of the invention, the angle formed by base arm portion (83) and sidewall arm portion (86) is 90° (e.g., at elbow portion 89).

Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims. 

1. An externally supported lye tank comprising: (a) a lye tank having a base and sidewalls extending away from said base, and having an open end, the base of said lye tank having an aperture therein, said lye tank being fabricated from a material selected from the group consisting of metal, plastic and combinations thereof, the base and sidewalls of said lye tank each having external surfaces; and (b) an external support structure comprising, (i) at least one bowl-shaped profile member having a base and sidewalls extending away from said base, said bowl-shaped profile member having an open end, the sidewalls and base of said bowl-shaped profile having internal surfaces which together define an interior space of said bowl-shaped profile, said base of said bowl-shaped profile member having an external surface, said bowl-shaped profile being fabricated from a material selected from the group consisting of metal, plastic and combinations thereof, and said bowl-shaped profile member having a first end and a second end, (ii) a plurality of plastic reinforcing ribs located within said interior space of said bowl-shaped profile, said plastic reinforcing ribs being fixedly attached to said bowl-shaped profile member by means selected from the group consisting of positive connections, material connections and combinations thereof, and (iii) a connecting member having an opening, said connecting member being connected to the first end of said bowl-shaped profile member by means selected from the group consisting of positive connections, material connections and combinations thereof, wherein said lye tank and said external support structure are joined together such that the aperture in the base of said lye tank is aligned with the opening of said connecting member, the external surfaces of the base of bowl-shaped said profile member facing and being arranged along the external surfaces of said base and said sidewalls of said lye tank.
 2. The externally supported lye tank of claim 1 wherein said bowl-shaped profile member has a base arm portion that extends along said base of said lye tank, and a sidewall arm portion that is extends along said sidewall of said lye tank, said base arm portion and said sidewall arm portion of said bowl-shaped profile member being continuous and forming a substantially 90° angle with each other.
 3. The externally supported lye tank of claim 1 wherein said external support structure further comprises a plastic ring connected to the second end of said bowl-shaped profile member, said lye tank further comprising an outwardly extending annular flange positioned at an upper terminus of said sidewalls of said lye tank, said plastic ring of said external support structure and said annular flange of said lye tank engaging lockingly with each other.
 4. The externally supported lye tank of claim 1 wherein said external support structure comprises three bowl-shaped profile members, which are arranged at equal distances along the periphery of said connecting member.
 5. The externally supported lye tank of claim 1 wherein said connecting member has edge regions having perforations, and the first end of said bowl-shaped profile member has edge regions having perforations, the edge regions and perforations of said connecting member being positioned above the edge regions and perforations of said bowl-shaped profile member, and thermoplastic material being injected through the perforations and around the positioned edge regions of said connecting member and said bowl-shaped profile member.
 6. The externally supported lye tank of claim 1 wherein said bowl-shaped profile member and said connecting member are each fabricated from a metal selected independently from the group consisting of steel, nickel, chromium, iron, copper, zinc, titanium, scandium, aluminium, magnesium, and alloys of at least two metals thereof.
 7. The externally supported lye tank of claim 1 wherein said lye tank is fabricated from a thermoplastic material selected from the group consisting of polycarbonate (PC), polyurethane (PU), polyester, polystyrene (PS), acrylonitrile butadiene styrene (ABS) graft copolymer, polypropylene oxide (PPO), polysulphone (PSO), polyphenylene sulphide (PPS), polyimide (PI), polyketone (PEEK), polyamide (PA), polypropylene (PP), polyethylene (PE) and combinations thereof.
 8. The externally supported lye tank of claim 7 wherein said thermoplastic material comprises a material selected from the group consisting of reinforcing material, filler material and combinations thereof.
 9. The externally supported lye tank of claim 3 wherein said plastic reinforcing ribs and said plastic ring are each fabricated from a thermoplastic material selected independently from the group consisting of polycarbonate (PC), thermoplastic polyurethane (PU), polyester, polystyrene (PS), acrylonitrile butadiene styrene graft copolymer (ABS), polypropylene oxide (PPO), polysulphone (PSO), polyphenylene sulphide (PPS), polyimide (PI), polyketone (PEEK), polyamide (PA), polypropylene (PP), polyethylene (PE) and combinations thereof.
 10. The externally supported lye tank of claim 9 wherein said thermoplastic material comprises a material selected from the group consisting of reinforcing material, filler material and combinations thereof.
 11. The externally supported lye tank of claim 1 wherein said sidewalls and base of said bowl-shaped profile member have a plurality of perforations having edges, further wherein said plastic reinforcing ribs are formed by injection molding thermoplastic material onto the internal surfaces of said sidewalls and said base of said bowl-shaped profile member, a portion of the injected-on thermoplastic material extending through the perforations in the base and sidewalls of said bowl-shaped profile member, the edges of the perforations being embedded in the thermoplastic material extending there through, thereby fixedly attaching said reinforcing ribs to said bowl-shaped profile member by means of positive connections.
 12. The externally supported lye tank of claim 1 wherein said reinforcing ribs are fixedly attached to said bowl-shaped profile member by means of material connections selected from the group consisting of, fasteners, snap fittings, clip-on fittings, adhesives and thermoplastic welds. 